Re: st: cumulative summation

bysort firm year (ties) : replace ties = ties[_N]
Nick
On Tue, Feb 26, 2013 at 7:08 AM, James Bernard <jamesstatalist@gmail.com> wrote:
> I have used the sum function to calculate a variable in a panel data.
>
> Firm Year ties
> ----------- ---------- -------
> A 1990 1
> A 1990 2
> A 1991 1
> B 1990 0
> B 1990 1
> B 1990 3
> C 1990 0
> C 1991 0
> C 1992 0
>
> The issue is that the variable ties which is the number of ties a firm
> has formed in a year is a cumulative sum of something and, therefore,
> for a company like A the final number of ties in year 1990 should be
> 2. I need the program to write the same number (final value of the
> cumulative sum) instead of 1.
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